(CNN) -- The brutal killing of a British soldier Wednesday near a military barracks in the Woolwich neighborhood of southeast London has shocked the United Kingdom, with Prime Minister David Cameron and other officials calling it a terrorist attack.
Security was increased at army bases around London amid fears of additional attacks. The capital has not witnessed an alert of this kind since the summer of 2005, when London's public transport network was targeted with coordinated bomb attacks.
Two men accused of carrying out the attack were shot by police and are under guard at hospitals.
-- Two additional arrests were made by police Thursday tied to their investigation into the killing of a soldier in Woolwich, London's Metropolitan Police said on the department's official Twitter account. They were a 29-year-old man and a 29-year-old woman, both taken into custody "on suspicion of conspiracy to murder."
-- Friends and acquaintances, as well as British media, named the meat-cleaver wielding man shown in a video aired by ITN after the attack as Michael Adebolajo. The other three suspects arrested -- including the one arrested at the scene along with Adebolajo -- have not yet been identified.
-- Adebolajo and the other man arrested in Woolwich were in stable condition at separate South London hospitals Thursday evening, the Metropolitan Police tweeted.
-- Abu Barra described his friend, Adebolajo, as a "very caring" man who was "very vocal" about his belief that Muslims worldwide were being oppressed. "I wasn't surprised that (the attack) happened," Barra told CNN. "...As long as (British) foreign policy is engaging in violence, they're only inviting violence in retaliation."
-- Warranted searches have been carried out at six residential addresses as part of what police described as "a large, complex and fast-moving investigation which continues to develop."
-- It is understood that the two people suspected of carrying out the knife attack were known to Britain's domestic security service. They had featured in previous investigations into other people but were not themselves under surveillance.
-- Prominent British Muslim radical leader Anjem Choudary said he knew one of the men named on social media as carrying out the attack.
-- The soldier they killed was 25-year-old Lee Rigby, the father of a 2-year-old boy, the UK Ministry of Defense said. Rigby, described as "always smiling," served as a machine gunner, played in the military's Corps of Drums, had been deployed to Afghanistan and was a recruiter in London at the time of his death, the military said.
-- "We have lost a brave soldier," Cameron said Thursday outside 10 Downing Street.
-- The prime minister had cut shot a visit to Paris and rushed back to London, where he led a crisis meeting of top officials Thursday. Those in attendance included Home Secretary Theresa May, Defense Secretary Philip Hammond, London Mayor Boris Johnson and senior police and security officials.
-- A video recorded by one of the two men immediately after the attack seemed to suggest a jihadist agenda. Cameron addressed the issue of Muslim extremism: "This was not just an attack on Britain and on our British way of life. It was also a betrayal of Islam and of the Muslim communities who give so much to our country. There is nothing in Islam that justifies this truly dreadful act."
-- British Muslim groups registered horror over the killing of Rigby by attackers who said they were acting to avenge Muslim deaths overseas. Muslim commentators also suggested there is more that British leaders can do to address issues in their community, particularly among alienated young men.
-- Police have deployed an extra 1,200 officers at key locations, including religious institutions and transportation hubs, police official Mark Rowley said.
-- Capt. William Russell, a U.S. Air Force official, said Thursday that "there are no force protection changes at our UK air bases in response to the incident in London."
-- U.S. President Barack Obama on Thursday condemned "in the strongest terms" the brutal killing of a British soldier in southeast London. "The United States stands resolute with the United Kingdom, our ally and friend, against violent extremism and terror," Obama said. "... Our special relationship with the United Kingdom is especially important during times of trial."
-- Cameron himself offered a message of determination Thursday, saying his "country will be absolutely resolute in its stand against violent extremism and terror." "We will never give in to terror -- or terrorism -- in any of its forms," the prime minister said.
CNN's Greg Botelho and Dan Rivers contributed to this report.